In recent years, hybrid and electric vehicles, which are provided with a battery, have been proposed, and some of them have been put into practice, to effectively use energy, in particular, regenerative energy as environmental measures. Typically, secondary batteries, which have been put to into practice and installed in vehicles so far, include, for example, lead storage batteries, nickel metal hydride batteries, or high powered lithium ion batteries. Some electric vehicles, such as electric cars, charge their batteries by plugging in the electric vehicle at a charging station. Other electric vehicles such as electric trains and light rail cars, are permanently connected to a power source through hardware in the railing or through overhead lines.
Recent trends in integrated transportation systems for electric vehicles, such as bus systems or other public transportation systems, have moved away from the use of permanent electrical connections to electric vehicles, as these systems are an eyesore, are unpopular, are costly to install and maintain, and can be unsafe. Some of these systems do not enable an electrical vehicle to run independent of a railing or overhead line. The speed of charging can be very pertinent for a heavy-duty vehicle, such as a bus, that may be regularly recharged within small time frames. More recent integrated transport systems may use fixed charging stations to rapidly charge heavy duty batteries used in electric vehicles. In one example, an electric vehicle may need to complete a charge in less than ten minutes that is sufficient to enable it to complete its normal route of nine to twelve miles in an hour before having to recharge.
One current common charging strategy for electric vehicles is to use a “worst case scenario” strategy where the battery cells for an electric vehicle are fully charged or charged as much as possible during each charging event. This may be optimal, for example, if the range of the electric vehicle needs to be maximized, if it may be difficult to predict the next charging event, or if consumption of the charge of the electric vehicle in the near future is unpredictable. However, such a charging strategy may result in cycling of the batteries within a state of charge (SOC) range that may be damaging or detrimental for the life of the batteries. Most battery cells tend to have a “sweet spot” for charging in the lower SOC range, which may be 10-40% of total charge, 20-60% of total charge, or another range, depending upon the battery chemistry used and the specific configuration used in the electric vehicle.
Thus, a need exists for a systems and methods for maximizing the battery life of electric vehicles by maximizing SOC cycling in less damaging areas of the SOC range.